Figure 5.

R loops transcriptionally regulate ncRNAs. (A) In plants, COOLAIR antisense lncRNA controls the expression of the FLC gene. R loops form over the promoter region of COOLAIR and are stabilized by the ssDNA-binding protein AtNDX. This causes transcriptional repression of COOLAIR and, ultimately, activation of the FLC gene. (B) In human neuronal cells, topoisomerase inhibitor topotecan causes accumulation of R loops in the G-rich termination region of the Snord116 gene. This causes chromatin decondensation and blocks read-through transcription that otherwise forms the Ube3a antisense transcript. This activates the expression of the Ube3a sense transcript. Arrows indicate the direction of transcription. For simplicity, nucleosomes are omitted. The diagram is not drawn to scale.